Extrusion die

ABSTRACT

An extrusion die is disclosed for forming tubular extrusions from billets. The extrusion die comprises a die ring having an interior surface defining a bore. A spider is positioned within the die ring bore having a mandrel and a plurality of angularly spaced legs disposed against the die ring bore surface with the leg ends disposed in spaced relation with the mandrel. A sealing ring is positioned within the die ring bore in abutment with the spider leg ends and with the die ring bore surface, the sealing ring having a central aperture and a planar surface disposed transverse the bore axis. A die cap is provided having a planar surface disposed in abutment with the sealing ring planar surface and having an aperture extending through the die cap from a rim within the die cap planar surface, the rim being disposed in spaced relation about the mandrel. Means are also provided for holding the die cap and spider together with the sealing ring sandwitched therebetween.

United States Patent [191 Robertson 1 Sept. 10, 1974 EXTRUSION DIE [76] Inventor: Harry M. Robertson, PO. Box 291,

Raymond, Ga. 30271 [22] Filed: Mar. 30, 1973 [21] Appl. No.: 346,352

Primary Examiner-Charles W. Lanham Assistant Examiner-Robert M. Rogers Attorney, Agent, or FirmNewton, Hopkins & Ormsby [5 7] ABSTRACT An extrusion die is disclosed for forming tubular extrusions from billets. The extrusion die comprises a die ring having an interior surface defining a bore. A spider is positioned within the die ring bore having a mandrel and a plurality of angularly spaced legs disposed against the die ring bore surface with the leg ends disposed in spaced relation with the mandrel. A sealing ring is positioned within the die ring bore in abutment with the spider leg ends and with the die ring bore surface, the sealing ring having a central aperture and a planar surface disposed transverse the bore axis. A die cap is provided having a planar surface disposed in abutment with the sealing ring planar surface and having an aperture extending through the die cap from a rim within the die cap planar surface, the rim being disposed in spaced relation about the mandrel. Means are also provided for holding the die cap and spider together with the sealing ring sandwitched therebetween.

15 Claims, 3 Drawing Figures EXTRUSION DIE BACKGROUND OF THE INVENTION This invention relates generally to extrusion dies, and particularly to tapered seal type dies used in forming tubular extrusions.

l-Iollow dies used in forming tubular extrusions from billets of metal such as aluminum, copper and alloys are usually either of the bridge or tapered seal type. The bridge type extrusion dies are generally cheaper to manufacture and easier to work with than the tapered seal type. However, the tapered seal type dies do enable the user to take full advantage of the metallic billet from which the extrusion is formed, and do tend to trap less air than the bridge type.

Tapered seal type extrusion dies normally comprise a die ring having a conical bore into which a spider is placed. The spider comprises a mandrel which forms the center void in the tubular extrusions, and a set of angularly spaced legs formed integrally with the mandrel. The feet or ends of the spider legs are disposed in spaced relation about the mandrel. The sides of the legs typically form segments of a tapered, conical surface whereby the legs may be placed flushed against the die ring bore surface. An end cap is placed within the die ring bore and secured to the spider leg ends. The end cap restricts the thickness of the molten metal flowing from the billet about the periphery of the mandrel thereby shaping the outer surface of the extrusion.

The difficulty heretofore experienced in manufacturing and using the tapered seal type dies has been attributable in large measure to the size and complex configuration of the end cap die members. The periphery of these end caps has had to have the same taper as that of the die ring bore in order to form a seal therewith. The end caps have also had to have an end surface formed to mate with the spider leg ends plus a set of holes formed in registry with holes in the spider leg ends to accomodate a set of threaded bolts or the like to secure these members together. They also have had to have a narrowing of the central aperture to form a close restriction about the mandrel to form the outer surface of the extrusion. These various contours in the surface of the end cap have provided close spaces or pockets in which molten metal solidifies during and after use of the die in forming extrusions. The solidifications in these restricted spaces are very difficult to remove during die cleaning operations and also impede disassembly. The relatively complex surfaces also render manufacture of the end cap members difficult and costly.

Once an end cap die member wears to the point where replacement becomes required the spider must ordinarilly be shipped to the die manufacturer in order to form the end cap with proper clearance about the mandrel. A taper also has to be turned. Should the peripheral taper become uneven replacement is usually required since turning would be accomplished only at an attendant sacrifice in peripheral material creating spacings between the'die cap periphery and the die ring bore when inserted into the bore and run up against a seated spider. Where cleaning is attempted as with a caustic agent without removal of the end cap the restriction provided by the end cap about the mandrel severly inhibits the flow of the caustic agent.

Accordingly, it is a general object of the present invention to provide an improved extrusion die.

More specifically, it is an object of the present invention to provide an extrusion die with improved means for forming the outer surface of tubular extrusions.

Another object of the invention is to provide a tapered seal type extrusion die which is relatively easy to work with and to clean.

Another object of the invention is to provide a relatively inexpensive tapered seal extrusion die.

Yet another object of the invention is to provide a tapered seal extrusion die for which replacement end caps may be manufactured without need for delivery of associated parts to the replacement manufacturer.

Another object is to provide a taper die that has a cap free of die ring bore surface to allow realignment without returning taper or replacement cap without having to turn a taper.

SUMMARY OF THE INVENTION In one form of the invention an extrusion die is provided for forming tubular extrusions from billets and comprising a die ring having an interior surface defining a bore. A spider is positioned within the die ring bore having a mandrel and a plurality of angularly spaced legs disposed against the die ring bore surface with the leg ends disposed in spaced relation with the mandrel. A sealing ring is positioned within the die ring bore in abutment with the spider leg ends and with the die ring bore surface, the sealing ring having a central aperture and a planar surface disposed transverse the bore axis. A die cap is provided having a planar surface disposed in abutment with the sealing ring planar surface and having an aperture extending through the die cap from a rim within the die cap planar surface, the rim being disposed in spaced relation about the mandrel. Means are also provided for holding the die cap and spider together with the sealing ring sandwitched therebetween.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an exploded view in prospective of a tapered seal extrusion die embodying principles of the invention in one form.

FIG. 2 is a cross-sectional view of an assembled portion of the extrusion die illustrated in FIG. 1.

FIG. 3 is a rear view in elevation of two end cap members secured to a sealing ring which members may be used with an extrusion die embodying principles of the invention in another form and which uses enabled two tubular extrusions to be formed simultaneously.

DETAILED DESCRIPTION OF THE DRAWING Referring now in more detail to the drawing, there is shown in FIGS. 1 and 2 a tapered seal extrusion die comprising a die ring 10 having a tapered, interior conical surface 12 forming a bore. The exterior surface of the die ring is in the shape of a stepped cylinder. Notwithstanding the term die ring the exterior surface need not, of course, be annular.

Within the die ring bore is seated a spider 14 having a cylindrical mandrel 16 disposed along the axis of the conical die ring bore. The spider also has four angularly spaced legs 18 having their feet or ends 20 disposed in spaced relation about mandrel 16. The radially outer surfaces of legs 18 form conic segments adapted to fit flush against the conical surface 12 of the die ring.

A centrally apertured sealing ring 22 is disposed within the die ring bore with embossments 24 flush against the ends of spider legs 18. Lip 26 of outer, conical surface of the sealing ring projects slightly beyong the coplanar surfaces of the embossments and is seated snuggly within steps formed in the ends of the spider legs. The rear surface of the sealing ring is planar.

A die cap 30 also resides within the die ring bore with a planar die cap surface 32 in abutment with the planar surface of the sealing ring. The die cap has a central aperture extending from a circular rim or bearing 33 formed within end cap surface 32. That portion of the aperture adjacent rim 33 is cylindrical and communicates with a conical portion of the aperture which flares from the cylindrical portion. The periphery surface 34 of the end cap is cylindrical. Four spaced holes are provided through the end cap in alignment with four holes 21 through sealing ring 22 and four holes, not shown, in leg ends 20. These holes are adapted to receive detents such as four threaded bolts 37 or two bolts and four short dowel pins, not shown, which pass through the end cap and sealing ring holes and into the spider legs.

For operation, spider l4, sealing ring 22 and end cap 30 are placed within the die ring bore 10 and secured together, by bolts 37. The die ring 10 and inter parts are placed into die slide 40 in front of bolster and sub-bolster 46 that are also in die slide 40. The die slide 40 with inter parts is placed in front of pressure ring 48 disposed within platen 49. The container 42 having a lever 44 therewithin is closed against die ring 10 with all parts aligned. A billet of metal 50 is then placed within the container liner. While heated to a temperature just below melting the billet is rammed against spider 18 by a dummy block 52 and stem 54. Under the pressure so generated metal from the billet flows over the mandrel between legs 18, through the central aperture of sealing ring 22, and about the periphery of mandrel l6. Continued pressure exerted by the dummy block and stem forces the metal to flow through the hollow, cylindrical spacing about the mandrel and end cap and into the form of a solidified tubular extrusion 55 within bolster 45. The extrusion so formed then passes through the series of central apertures within bolster 45, sub-bolster 46, pressure ring 48, platen 49 and on to a cooling table, not shown.

Where desired, several tubular extrusions may be formed simultaneously through the use of multiple spider mandrels and multiple apertures within a unitary end cap. Alternatively, such may be accomplished through the use of multiple end caps in accordance with the invention such as the set of two coplanar end caps and 62 shown in FIG. 3. Each of these two end caps 60 and 62 is in the shape of a half disc. Each has an aperture into which one of two cylindrical spider mandrels 63 is coaxially positioned in spaced relation with the aperture forming surfaces of the end caps. The end caps are held by bolts 66 to a sealing ring 65 having a cross-axis surface sealing the gap between the two end caps. If desired, both end caps 60 and 62 may each have more than one aperture for simultaneously forming an even larger number of extrusions. In accomplishing this more than two coplanar end caps could be provided with each having a single aperture disposed adjacent a spider mandrel.

Extrusion dies of the type just described are relatively less expensive for tapered seal type dies. Savings in costs are achieved, in part, by the disc-shaped configuration of the end cap. The end cap is relatively thin and thus can be formed from smaller blanks of material such as steel and so fomied with the use of shorter end mills which exhibit less propensity for breaking. That the periphery of the end cap is cylindrical rather than conical and does not have to mate with the die ring bore surface provides further advantages over the prior art dies. With less complex surfaces manufacture of the sealing ring and end cap may be performed with greater use of saws and grinders and less use of lathes. The necessity of having to mill out and polish numerouspockets is also lessened. The smallness of the sealing ring and end cap renders each easy to handle and to align. The fact that the end cap may be a flat disc enhances this ease of handling even further.

Replacement of worn die components is relatively easy with extrusion dies of the type. just described which ease, in turn, results in shortened turn around time. The facility with which original set up as well as of replacement is accomplished permits the use of less skilledand therefore less expensive labor. In addition, replacement parts may be manufactured without having to ship the spider to the die manufacturer. Peripheral wear of the end cap does not create a break in the die seal and thus is of little importance. However, if desired a new peripheral surface may be tumed on mandrel and sealing ring even though it be smaller than the original surface. This adjustment can be made by adding to the thickness of a new end cap having the same effect as a new die with the replacement of only one,

part.

For cleaning the various components of the die may be disassembled with relative ease. Solidified pockets of molten metal may be reached and flushed well with caustic agents by removing the die cap from about the mandrel and leaving the sealing ring temporarily in place. With the end cap so removed the caustic agent may readily flow through the enlarged central aperture within the sealing ring to attack the solidifications.

For turn around after a short period in a caustic agent 45 just long enough to clear the die bearings (rims) of so- 1. An extrusion die for forming tubular extrusions from billets, said extrusion die comprising:

a die ring having an interior surface defining a tapered bore having a bore axis;

a spider removably positioned within said die ring bore and having a mandrel and a plurality of angularly spaced legs disposed against said die ring bore surface with the ends of said legs disposed in spaced relation with said mandrel;

a tapered sealing ring positioned within said die ring bore in abutment with said spider leg ends and with.

said die ring ,b,ore surface, sai,d sealing ring having a planar surface disposed transverse said bore axis and a central aperture;

a die cap having a planar surface disposed in abutment with said sealing ring planar surface and having an aperture extending through said die cap from a rim within said die cap planar surface, said rim being disposed in spaced relation about said mandrel; and

means for holding said die cap and spider together with said sealing ring sandwiched therebetween.

2. An extrusion die in accordance with claim 1 wherein said sealing ring and said die cap and said spider legs have a set of aligned holes adapted to receive detents.

3. An extrusion die in accordance with claim 1 wherein said die cap is disc-shaped.

4. An extrusion die in accordance with claim 1 wherein the periphery of said sealing ring is conical and the periphery of said die cap is cylindrical.

5. An extrusion die in accordance with claim 1 wherein each of said spider leg ends has a step, and wherein said sealing ring has a peripheral rim disposed in abutment with said spider leg end steps.

6. An extrusion die in accordance with claim 1 wherein said mandrel is cylindrical and is disposed along said bore axis.

7. An extrusion die in accordance with claim 1 wherein said spider has a plurality of mutually spaced mandrels, and wherein said die cap has a plurality of apertures extending through said die cap from a plurality of rims within said die cap planar surface, said rims being respectively disposed in spaced relation about said mandrels.

8. An extrusion die for forming tubular extrusions from billets, said extrusion die comprising:

a die ring having a conical interior surface defining a conical bore having a bore axis;

a spider having a peripheral surface removably positioned within said die ring bore against said die ring conical bore surface, and at least one mandrel disposed in spaced relation with said die ring conical interior surface;

a sealing ring positioned within said die ring bore in abutment with said spider and with said die ring conical bore surface, said sealing ring having a planar surface disposed transverse said bore axis and an aperture through which said spider mandrel passes; I die cap having a planar surface disposed in abutment with said sealing ring planar surface and with an aperture defining surface disposed in spaced relation adjacent said mandrel; and means for holding said die ring, said spider, said sealing ring, and said die cap rigidly together.

9. An extrusion die in accordance with claim 8 wherein a portion of said mandrel is cylindrical, wherein a first portion of said die cap aperture defining surface is cylindrical, and wherein said cylindrical portion of said mandrel is disposed within said cylindrical first portion of said die cap aperture defining surface.

10. An extrusion die in accordance with claim 9 wherein a second portion of said die cap aperture defining surface is conical.

11. An extrusion die in accordance with claim 8 wherein said die cap is disc-shaped.

12. An extrusion die in accordance with claim 8 wherein said peripheral surface of said spider is segmented.

13. An extrusion die for forming tubular extrusions from billets, said extrusion die comprising:

a die ring having an interior surface defining a tapered bore having a bore axis;

a spider removably positioned within said die ring bore and having first and second mutually spaced mandrels and a plurality of angularly spaced legs disposed against said die ring bore surface with the ends of said legs disposed in spaced relation about said mandrels;

a sealing ring positioned within said die ring bore in abutment with said spider leg ends and with said die ring bore surface, saidsealing ring having a planar surface disposed transverse said bore axis and first and second spaced apertures;

a first die cap member having a planar surface disposed in abutment with a portion of said sealing ring planar surface and having an aperture extending through said first die cap member from a rim within said first die cap member planar surface, said rim being disposed in spaced relation about said first mandrel;

a second die cap member having a planar surface disposed in abutment with a portion of said sealing ring surface and having an aperture extending through said second die cap member from a rim within said second die cap planar surface, said rim being disposed in spaced relation about said second mandrel; and

means for holding said first and second die cap members to said spider legs with said sealing ring sandwiched therebetween.

14. An extrusion die in accordance with claim 13 wherein said first and second die cap members are substantially coplanar.

15. An extrusion die in accordance with claim 13 wherein said die ring interior surface is conical and wherein a portion of the peripheral surfaces of said first and second die cap members are cylindrical. 

1. An extrusion die for forming tubular extrusions from billets, said extrusion die comprising: a die ring having an interior surface defining a tapered bore having a bore axis; a spider removably positioned within said die ring bore and having a mandrel and a plurality of angularly spaced legs disposed against said die ring bore surface with the ends of said legs disposed in spaced relation with said mandrel; a tapered sealing ring positioned within said die ring bore in abutment with said spider leg ends and with said die ring bore surface, said sealing ring having a planar surface disposed transverse said bore axis and a central aperture; a die cap having a planar surface disposed in abutment with said sealing ring planar surface and having an aperture extending through said die cap from a rim within said die cap planar surface, said rim being disposed in spaced relation about said mandrel; and means for holding said die cap and spider together with said sealing ring sandwiched therebetween.
 2. An extrusion die in accordance with claim 1 wherein said sealing ring and said die cap and said spider legs have a set of aligned holes adapted to receive detents.
 3. An extrusion die in accordance with claim 1 wherein said die cap is disc-shaped.
 4. An extrusion die in accordance with claim 1 wherein the periphery of said sealing ring is conical and the periphery of said die cap is cylindrical.
 5. An extrusion die in accordance with claim 1 wherein each of said spider leg ends has a step, and wherein said sealing ring has a peripheral rim disposed in abutment with said spider leg end steps.
 6. An extrusion die in accordance with claim 1 wherein said mandrel is cylindrical and is disposed along said bore aXis.
 7. An extrusion die in accordance with claim 1 wherein said spider has a plurality of mutually spaced mandrels, and wherein said die cap has a plurality of apertures extending through said die cap from a plurality of rims within said die cap planar surface, said rims being respectively disposed in spaced relation about said mandrels.
 8. An extrusion die for forming tubular extrusions from billets, said extrusion die comprising: a die ring having a conical interior surface defining a conical bore having a bore axis; a spider having a peripheral surface removably positioned within said die ring bore against said die ring conical bore surface, and at least one mandrel disposed in spaced relation with said die ring conical interior surface; a sealing ring positioned within said die ring bore in abutment with said spider and with said die ring conical bore surface, said sealing ring having a planar surface disposed transverse said bore axis and an aperture through which said spider mandrel passes; a die cap having a planar surface disposed in abutment with said sealing ring planar surface and with an aperture defining surface disposed in spaced relation adjacent said mandrel; and means for holding said die ring, said spider, said sealing ring, and said die cap rigidly together.
 9. An extrusion die in accordance with claim 8 wherein a portion of said mandrel is cylindrical, wherein a first portion of said die cap aperture defining surface is cylindrical, and wherein said cylindrical portion of said mandrel is disposed within said cylindrical first portion of said die cap aperture defining surface.
 10. An extrusion die in accordance with claim 9 wherein a second portion of said die cap aperture defining surface is conical.
 11. An extrusion die in accordance with claim 8 wherein said die cap is disc-shaped.
 12. An extrusion die in accordance with claim 8 wherein said peripheral surface of said spider is segmented.
 13. An extrusion die for forming tubular extrusions from billets, said extrusion die comprising: a die ring having an interior surface defining a tapered bore having a bore axis; a spider removably positioned within said die ring bore and having first and second mutually spaced mandrels and a plurality of angularly spaced legs disposed against said die ring bore surface with the ends of said legs disposed in spaced relation about said mandrels; a sealing ring positioned within said die ring bore in abutment with said spider leg ends and with said die ring bore surface, said sealing ring having a planar surface disposed transverse said bore axis and first and second spaced apertures; a first die cap member having a planar surface disposed in abutment with a portion of said sealing ring planar surface and having an aperture extending through said first die cap member from a rim within said first die cap member planar surface, said rim being disposed in spaced relation about said first mandrel; a second die cap member having a planar surface disposed in abutment with a portion of said sealing ring surface and having an aperture extending through said second die cap member from a rim within said second die cap planar surface, said rim being disposed in spaced relation about said second mandrel; and means for holding said first and second die cap members to said spider legs with said sealing ring sandwiched therebetween.
 14. An extrusion die in accordance with claim 13 wherein said first and second die cap members are substantially coplanar.
 15. An extrusion die in accordance with claim 13 wherein said die ring interior surface is conical and wherein a portion of the peripheral surfaces of said first and second die cap members are cylindrical. 